Nuclear magnetic moments from NMR spectra—Experimental gas phase studies and nuclear shielding calculations

Abstract

Abstract NMR spectra of gaseous compounds and quantum chemical calculations are combined to determine new accurate values of magnetic dipole moments for a series of nuclei. We have analyzed shielding constants, resonance frequencies, and nuclear magnetic moments for a group of simple molecules. The chemical shifts and resonance frequencies are measured at 300 K and extrapolated to the zero‐density limit in order to remove all the intermolecular effects from the experimental parameters. The absolute shielding constants in the studied molecules are obtained from ab initio calculations. Assuming the proton magnetic moment as the reference, we determine the nuclear magnetic moments of 13 C, 14 N, 15 N, 17 O, 19 F, 29 Si, 31 P, 33 S, and 73 Ge. The new nuclear magnetic moments are consistent with the experimental NMR parameters, and using these new values one can for the first time predict successfully the shielding constant of a nucleus in a molecule when the corresponding resonance frequency is known. © 2007 Wiley Periodicals, Inc. Concepts Magn Reson Part A 30A: 246–260, 2007.